With the advancement of various technologies, electronic devices such as mobile phones, home appliances, PCs, PDAs, LCDs, and the like, have changed from analog type devices to digital type devices and have tended to have a higher processing speed due to an increase in amounts of processed data. In line with this, USB 2.0, USB 3.0, and high-definition multimedia interface (HDMI) have become prevalent as high-speed signal transmission interfaces and have been used in digital devices such as personal computers and digital HD televisions.
Such high speed interfaces employ a differential signal system which transmits a differential signal (differential mode signal) using a pair of signal lines, unlike single-end transmission systems which have generally been used in the art. However, high-speed digitalized electronic devices are sensitive to external stimuli, involving frequent signal distortion due to high frequency noise.
Such an abnormal voltage and noise result from a switching voltage generated in a circuit, power noise included in a source voltage, an unnecessary electromagnetic signal, electromagnetic noise, and the like, and a common mode filter (CMF) is used to prevent the introduction of such an abnormal voltage and high frequency noise to a circuit.